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9. Separation between Occupancies

9.1 Where a building is used for different type of occupancy, they should be separated by walls and floors having an FRP of not less than that required for the elements of construction of the compartment in which they are situated, subject to a maximum of 2 hours.

9.2 Occupancies for use for retail or as offices do not require such separation, provided that they are under a common and effective management and a common fire alarm system, actuated by a sprinkler alarm or by break glass points, is installed. The Building Authority has to be satisfied that the different occupancies are under a common management and that such management is effective.

9.3 Except for shopping arcades, every internal corridor serving rooms or flats in different occupancies should be separated from such occupancies by walls having an FRP of not less than 1 hour. The doorway giving access from the rooms or flats to the internal corridor should have a door with an FRP of not less than 1/2 hour. Fixed lights having an FRP of not less than 1/2 hour may be installed in such separating walls at a height of not less than 1.8 m.

9.4 Except where the means of escape is in two directions, balcony approach serving rooms or flats in different occupancies should be separated from such occupancies by walls having an FRP of not less than 1 hour. The doorway giving access from the rooms or flats to the balcony approach should be provided with a door having an FRP of not less than 1/2 hour. Fixed lights having an FRP of not less than 1/2 hour may be installed in such separating walls at a height of not less than 1.8 m.

10. Openings through Fire Resisting Walls and Floors

10.1 Openings may be made in compartment walls for communication, but not combination, of adjoining compartments, provided that any such opening is protected by a door or a fire shutter with the same FRP as the wall with regard to the criteria of integrity and insulation. The criterion of insulation is not applicable to such doors and fire shutters when the total width of the openings to be formed is not more than 25% of the length of the compartment wall.

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that part of the external wall shall have an FRP of not less than that required for the wall separating such staircase or lobby from the remainder of the building. It should also be imperforate, unless protected by fixed light which should not occupy more than 25% of the area of the external wall of the storey in which it is located with an FRP as described in (iii) above or, in the case of the discharge point at ground level or roof level, a door with an FRP of not less than half that required for the wall. See diagram 3 for illustration.

11.8 Where the external wall coming under para 11.6 continues in the same plane with other external walls of the same building and both such walls have an FRP of less than that required for the wall separating the staircase or lobby concerned from the rest of the building, the remaining fire resisting walls of the staircase or lobby should, at the junction with such external wall, be extended for a distance of not less than 450 mm at any angle, except that at the ground level discharge the extension should not project beyond the external wall. See Diagram 4 for illustration.

12. Protection against Spread of Fire and Smoke between Floors

12.1 At any internal unprotected opening in floors within a compartment, such as those for escalators, circulation staircases or walkways in an atrium, a barrier of not less than 450 mm measured vertically downwards from the underside of the floor should surround the opening. The barrier should be constructed to have an FRP of not less than 1 hour. Floor openings tend to create vertical or horizontal drafts which permit the spread of fire and smoke. The barrier around such openings should serve to stop heated air and smoke properly and permit the control of fire at any point by local sprinklers. If false ceilings are hung in the vicinity of the opening, the barrier should extend not less than 450 mm below the false ceiling. Having regard to the difficulties in some situations in providing barriers due to low headroom or false ceilings, alternative installations may be provided, such as smoke reservoirs, perforate or open ceilings, dynamic smoke extraction system and smoke detector operated devices. Consideration may be given by Building Authority to such installations on the merits of each case and approval will depend on the demonstration of their effectiveness and proper control and management after completion. See Diagrams 5 and 6 for illustration.

AB : i)

ii)

iii)

iv)

opposite side of a street,

common boundary with an adjoining site,

any other external wall of FRP < FRPe or unprotected opening

of the same building,

any other building on the same site.

External wall may be unprotected if d > 6m

External wall with FRPe ≥ FRPs if d ≤ 6m

Openings : i) d ≤ 6m – fixed light with FRP ≥ 1/2 FRPe ;

– door with FRP ≥ 1/2 FRPe for :

*discharge point at G/F

*roof level

ii) d > 6m – unprotected